75.56% is what you get when you turn the fraction 68/90 into a percentage.
The fraction 68/90 can be simplified to 34/45, which still represents the same part of a whole. Seeing it as a percent makes it easier to compare with other numbers that are already in percent form.
In everyday situations, a value of 75.56% might describe a test score, a discount, or the portion of a project that’s finished. It shows that a little more than three‑quarters of the whole is covered.